diff --git a/frontend/css/tree-table.css b/frontend/css/tree-table.css
index 4acf08daf..1f16ad8d0 100644
--- a/frontend/css/tree-table.css
+++ b/frontend/css/tree-table.css
@@ -1,23 +1,202 @@
 /* Collapsible trees
  *
- * some of the shared styles are in `journal-table.css`
+ * some of the shared styles are in `journal-table.css`.
+ *
+ * The styles for .tree-table are not used in Fava anymore but are again provided
+ * for extensions for the near future.
  */
 
-.tree-table p {
+.tree-table-new p {
   margin-top: -1px;
 }
 
-.tree-table p > span {
+.tree-table-new p > span {
   margin-right: -1px;
   border: 1px solid var(--table-border);
 }
 
-.tree-table .num {
+.tree-table-new .num {
   /** Space for about 14 characters, so a number like 1234512345.123 fits. */
   width: 9em;
 }
 
-.tree-table .other {
+.tree-table-new .other {
   /** Space for about 18 (four more) characters, so an amount like 1234512345.123 USD fits. */
   width: 12em;
 }
+
+.tree-table.fullwidth {
+  display: block;
+  max-width: 100%;
+  overflow-x: auto;
+}
+
+.tree-table p {
+  margin-top: -1px;
+}
+
+.tree-table p > span {
+  margin-right: -1px;
+  border: 1px solid var(--table-border);
+}
+
+.tree-table .account-cell {
+  display: flex;
+  flex: 1;
+  align-items: center;
+  min-width: 14em;
+  max-width: 30em;
+}
+
+.tree-table .account-cell.depth-1 {
+  min-width: 13em;
+  max-width: 29em;
+  margin-left: 1em;
+}
+
+.tree-table .account-cell.depth-2 {
+  min-width: 12em;
+  max-width: 28em;
+  margin-left: 2em;
+}
+
+.tree-table .account-cell.depth-3 {
+  min-width: 11em;
+  max-width: 27em;
+  margin-left: 3em;
+}
+
+.tree-table .account-cell.depth-4 {
+  min-width: 10em;
+  max-width: 26em;
+  margin-left: 4em;
+}
+
+.tree-table .account-cell.depth-5 {
+  min-width: 9em;
+  max-width: 25em;
+  margin-left: 5em;
+}
+
+.tree-table .account-cell.depth-6 {
+  min-width: 8em;
+  max-width: 24em;
+  margin-left: 6em;
+}
+
+.tree-table .account-cell.depth-7 {
+  min-width: 7em;
+  max-width: 23em;
+  margin-left: 7em;
+}
+
+.tree-table .account-cell.depth-8 {
+  min-width: 6em;
+  max-width: 22em;
+  margin-left: 8em;
+}
+
+.tree-table .account-cell.depth-9 {
+  min-width: 5em;
+  max-width: 21em;
+  margin-left: 9em;
+}
+
+.tree-table .account-cell a {
+  margin-left: 1em;
+}
+
+.tree-table .has-children {
+  cursor: pointer;
+}
+
+.tree-table .has-children::before {
+  margin: 0 -10px 0 0;
+  content: "";
+  border-top: 5px solid var(--treetable-expander);
+  border-right: 5px solid transparent;
+  border-left: 5px solid transparent;
+}
+
+.tree-table .num {
+  width: 10em;
+}
+
+.tree-table .num a {
+  display: block;
+  color: inherit;
+}
+
+.tree-table .other {
+  width: 13em;
+}
+
+.tree-table .other a {
+  display: block;
+  color: inherit;
+}
+
+.tree-table .balance-children {
+  display: block;
+  opacity: 0.7;
+}
+
+.tree-table .has-balance .balance {
+  display: block;
+}
+
+.tree-table .has-balance .balance-children {
+  display: none;
+}
+
+.tree-table .toggled ol {
+  display: none;
+}
+
+.tree-table .toggled .balance {
+  display: none;
+}
+
+.tree-table .toggled .balance-children {
+  display: block;
+  color: var(--text-color);
+}
+
+.tree-table .toggled .has-children::before {
+  transform: rotate(270deg);
+}
+
+.tree-table .expand-all {
+  margin-left: 15px;
+  font-weight: normal;
+  color: inherit;
+  opacity: 0.5;
+}
+
+.tree-table .diff {
+  margin-right: 3px;
+  font-size: 0.9em;
+  color: var(--budget-zero);
+  white-space: nowrap;
+}
+
+.tree-table .diff.negative {
+  color: var(--budget-negative);
+}
+
+.tree-table .diff.positive {
+  color: var(--budget-positive);
+}
+
+/* For two or more operating currencies, set a slightly smaller size. */
+.two-currencies {
+  font-size: 0.9em;
+}
+
+.two-currencies .num {
+  width: 8em;
+}
+
+.two-currencies .other {
+  width: 11em;
+}
diff --git a/frontend/src/main.ts b/frontend/src/main.ts
index bf2692d48..4ba4808ff 100644
--- a/frontend/src/main.ts
+++ b/frontend/src/main.ts
@@ -45,6 +45,7 @@ import { SortableTable } from "./sort";
 import { errors, fava_options, ledgerData } from "./stores";
 import { ledger_mtime, read_mtime } from "./stores/mtime";
 import { SvelteCustomElement } from "./svelte-custom-elements";
+import { TreeTableCustomElement } from "./tree-table/tree-table-custom-element";
 
 /**
  * Define the custom elements that Fava uses.
@@ -57,6 +58,9 @@ function defineCustomElements() {
   customElements.define("fava-journal", FavaJournal);
   customElements.define("sortable-table", SortableTable, { extends: "table" });
   customElements.define("svelte-component", SvelteCustomElement);
+
+  // for extension compatibility
+  customElements.define("tree-table", TreeTableCustomElement);
 }
 
 router.on("page-loaded", () => {
diff --git a/frontend/src/tree-table/IntervalTreeTable.svelte b/frontend/src/tree-table/IntervalTreeTable.svelte
index 444d6549c..e62799022 100644
--- a/frontend/src/tree-table/IntervalTreeTable.svelte
+++ b/frontend/src/tree-table/IntervalTreeTable.svelte
@@ -44,7 +44,7 @@
   });
 </script>
 
-<ol class="flex-table tree-table">
+<ol class="flex-table tree-table-new">
   <li class="head">
     <p>
       <AccountCellHeader />
diff --git a/frontend/src/tree-table/TreeTable.svelte b/frontend/src/tree-table/TreeTable.svelte
index 1f72da2cc..c00014169 100644
--- a/frontend/src/tree-table/TreeTable.svelte
+++ b/frontend/src/tree-table/TreeTable.svelte
@@ -23,7 +23,10 @@
   $: $not_shown = $get_not_shown(tree, end);
 </script>
 
-<ol class="flex-table tree-table" class:wider={$operating_currency.length > 1}>
+<ol
+  class="flex-table tree-table-new"
+  class:wider={$operating_currency.length > 1}
+>
   <li class="head">
     <p>
       <AccountCellHeader />
diff --git a/frontend/src/tree-table/tree-table-custom-element.ts b/frontend/src/tree-table/tree-table-custom-element.ts
new file mode 100644
index 000000000..f873529a8
--- /dev/null
+++ b/frontend/src/tree-table/tree-table-custom-element.ts
@@ -0,0 +1,53 @@
+import { delegate } from "../lib/events";
+
+/**
+ * Account trees.
+ *
+ * This handles the toggling of accounts in the accounts trees.
+ *
+ * This is not used in Fava anymore but provided for extension compatibility.
+ */
+export class TreeTableCustomElement extends HTMLElement {
+  constructor() {
+    super();
+
+    const expandAllLink = this.querySelector(".expand-all");
+    expandAllLink?.addEventListener("click", () => {
+      expandAllLink.classList.add("hidden");
+      this.querySelectorAll(".toggled").forEach((el) => {
+        el.classList.remove("toggled");
+      });
+    });
+
+    delegate(this, "click", "span.has-children", (event: MouseEvent) => {
+      const { target } = event;
+      if (
+        !(target instanceof HTMLElement) ||
+        target instanceof HTMLAnchorElement
+      ) {
+        return;
+      }
+      const row = target.closest("li");
+      if (!row) {
+        return;
+      }
+      const willShow = row.classList.contains("toggled");
+      if (event.shiftKey) {
+        this.querySelectorAll("li").forEach((el) => {
+          el.classList.toggle("toggled", !willShow);
+        });
+      }
+      if (event.ctrlKey || event.metaKey) {
+        this.querySelectorAll("li").forEach((el) => {
+          el.classList.toggle("toggled", willShow);
+        });
+      }
+      row.classList.toggle("toggled");
+
+      expandAllLink?.classList.toggle(
+        "hidden",
+        !this.querySelectorAll(".toggled").length,
+      );
+    });
+  }
+}